Method and device for producing a nonwoven geotextile, and geotextile thus produced

ABSTRACT

A nonwoven geotextile includes: crushed plant stems ( 305 ) more than five millimeters in diameter; plant stem fragments ( 310 ); and plant fibers ( 315 ) partially attached to the crushed stems, wherein the plant stems and the plant stem fragments are interwoven by element of mechanical connections produced by spraying water. In preferred embodiments, the plants include hemp. The device for producing such a nonwoven geotextile includes: elements for arranging plants into a mat including crushed plant stems more than five millimeters in diameter, plant stem fragments and plant fibers partially attached to the crushed stems; and elements for spraying water onto the mat so as to form mechanical connections between the crushed plant stems, the plant stem fragments and the plant fibers of the mat.

TECHNICAL FIELD

The present invention relates to a method and a device for producing a nonwoven geotextile and a geotextile thus produced, in particular based on long plant fibers connected mechanically.

PRIOR STATE OF THE ART

Biodegradable geotextiles are usually produced in three ways:

-   -   from hand-woven coconut or hemp fibers or     -   from short fibers mechanically connected by mechanical         needlepunching methods using metal needles.     -   chemical assemblies with binders based, for example, on starch.

These techniques have several drawbacks. Firstly they are highly labor-intensive, secondly they are dependent on a geographic concentration of the fibers used, and thirdly their manufacture entails high production costs. The risk of blockages of the machinery's mechanisms compels manufacturers to use as input short fibers in the form of flakes (less than ten centimeters long), requiring a prior additional production step and restricting the choice of fibers.

Nonwovens, regardless of the fibers used, are refined beforehand, which entails complex and costly processes.

DESCRIPTION OF THE INVENTION

This invention aims to remedy all or part of these drawbacks. To this end, according to a first aspect, the present invention envisages a nonwoven geotextile comprising:

-   -   crushed plant stems having a diameter of more than five         millimeters,     -   plant stem fragments and     -   plant fibers partially attached to said crushed stems,         wherein the plant stems and the plant stem fragments are         interwoven by means of mechanical connections produced by         spraying water.

According to a second aspect, the present invention envisages a device for producing a nonwoven geotextile, which comprises:

-   -   a means for arranging plants into a mat comprising crushed plant         stems having a diameter of more than five millimeters, plant         stem fragments and raw plant fibers partially attached to said         crushed stems; and     -   a means for spraying water onto said mat so as to form         mechanical connections between the crushed plant stems, the         plant stem fragments and the plant fibers of said mat.

According to a third aspect, the present invention envisages a method for producing a nonwoven geotextile, which comprises

-   -   a step of arranging plants into a mat comprising crushed plant         stems having a diameter of more than five millimeters, plant         stem fragments and raw plant fibers partially attached to said         crushed stems; and     -   a step of spraying water onto said mat so as to form mechanical         connections between the crushed plant stems, the plant stem         fragments and the plant fibers of said mat.

Thanks to each of the aspects of the present invention, a geotextile is created with mechanical properties similar to, or even better than, those of known geotextiles, at lower cost. In effect, by eliminating the processing of the plants prior to forming the mat the complexity of the process is reduced. Moreover, the amount of labor required is small and production can be substantially automated.

The various aspects of the present invention thus make it possible to remove what is considered a technical impossibility linked to the use of stems and long fibers and to produce a nonwoven with better mechanical properties than the nonwoven geotextiles known from the prior art.

In addition, the risk of machine blockages is eliminated because the mechanical connections are created without contact, by spraying water.

According to particular features of each aspect of the invention, said plants comprise hemp.

According to particular features of the geotextile that is the object of the invention, the stems, stem fragments and plant fibers are coated with soil.

According to particular features of the geotextile that is the object of the invention, the soil comprises clay.

Thanks to each of these provisions, a layer of material is formed, hermetic in the case where clay is used, which makes it possible to form drains at minimal cost using natural materials.

According to particular features, the means for arranging plants into a mat of plant fibers comprises a means of crushing and/or carding plants.

According to particular features, the means for arranging plants into a plant fiber mat comprises a means of orienting fibers according to at least two different orientations, through the vibrating action of a carrier, or by intersecting supply paths.

According to particular features, the means for arranging plants into a plant fiber mat comprises a device for incorporating ropes or cables, parallel to the greatest length of the mat, intended to serve as guides.

It is noted that the origin of the ropes or cables can be plants or other, in particular plastic or metal.

According to particular features, the means for arranging plants into a plant fiber mat comprises a means of equalizing the thickness of the plant fiber mat.

According to particular features, the device that is the object of the invention comprises a means of coating the plant fiber mat with soil.

According to particular features of the device that is the object of the invention, the means of coating the plant fiber mat is designed to coat the plant fiber mat with soil comprising clay.

According to particular features, the method that is the object of the invention comprises a step of coating the plant fiber mat with soil.

According to particular features of the method that is the object of the invention, during the plant fiber mat coating step the plant fiber mat is coated with soil comprising clay.

The advantages, aims and special features of the geotextile that is the object of the present invention also constitute advantages, aims and special features of the method and device that are the objects of the present invention and vice versa. They are therefore not repeated here.

BRIEF PRESENTATION OF THE FIGURES

Other advantages, aims and characteristics of the present invention will become apparent from the description that will follow, made, as an example that is in no way limiting, with reference to the drawings included in an appendix, wherein:

-   -   FIG. 1 is a developed view of the device that is the object of         the present invention, in a particular embodiment,     -   FIG. 2 represents, in the form of a logical diagram, steps         utilized in a particular embodiment of the device that is the         object of the present invention,     -   FIG. 3 represents, schematically, a mat of stems, stem fragments         and fibers before spraying with water,     -   FIG. 4 represents, schematically, a mat of stems, stem fragments         and fibers before spraying with water and     -   FIG. 5 represents, schematically and in cross-section, a         realized drain based on a geotextile that is the object of the         present invention.

DESCRIPTION OF AT LEAST ONE EMBODIMENT

First of all, it is noted that the figures are not to scale.

FIG. 1 shows a device 105 for producing a geotextile 110. The device 105 comprises

-   -   a means 115 for arranging plants into a mat 125,     -   a means 165 of forming mechanical connections in said mat 125         and     -   optionally, a means 170 of coating the mat 125.

The plants are introduced at the inlet 140 of the device 105.

The means 115 of arranging the plants forms a mat, illustrated in FIG. 3, of crushed plant stems more than five millimeters in diameter, plant stem fragments and raw plant fibers partially attached to said crushed stems.

In the embodiment illustrated in FIG. 1, the means 115 of arranging the plants comprises:

-   -   a means 140 of inputting raw plants, in the form of large-sized         plants, typically stems measuring up to 2.5 m,     -   a means 145 of partially reducing stem plants, using a knife, to         form stem elements preferably more than a few centimeters long         and, even more preferably, more than ten centimeters long,     -   a means 150 of crushing and/or carding plants,     -   a means 155 of orienting fibers according to at least two         different orientations,     -   a means 160 of equalizing the thickness of the plant fiber mat         125, also referred to as compaction and batting.

Preferably, the plants used comprise hemp. In embodiments, the hemp is combined with stems of other plants to produce a nonwoven geotextile with a shorter lifespan and more rapid biodegrability. Such a geotextile is, for example, suitable for seasonal market gardening.

In embodiments, the means 155 of orienting fibers according to at least two different orientations operates by making a carrier of the mat 125 vibrate (the orienting means 155 comprises, for example, a vibratory corrugated plate, which distributes the fibers uniformly, in different directions), or by the intersection of supply paths.

In embodiments, the compaction and batting means 160 is formed of crusher rollers.

In embodiments (not shown), the means 115 for arranging plants into a plant fiber mat comprises a device for incorporating ropes or cables, parallel to the greatest length of the mat, intended to serve as guides, after the means 160. Thus, in order to facilitate the product's subsequent handling, guides (ropes, cables, threads) can be introduced in the depth of the mat 125.

Then, mechanical connections between the stem fragments and the fibers of the mat 125 are created in the depth of the mat 125 by the means 165 of forming connections. This means 165 operates by spraying water under pressure. More specifically, several lines of high-pressure jets perforate and/or crush parts of the stems, partially defibering them. In addition, fine materials “glue” and/or absorb the various fine elements.

On output from the device illustrated in FIG. 1, the finished geotextile 110 is made into rolls or semi-rigid sheets. The geotextile thus produced can then be processed according to use.

The device 105 is intended particularly for the production of nonwoven geotextiles to be used as a substitute for products used for “mulch” and in particular for replacing fabrics made from steeped jute or coconut fibers by hemp-based nonwovens.

In the case where the device comprises a coating means 170, coating with soil can be provided for. In particular, coating with soil containing clay, in particular consisting of pure clay, allows a watertight geotextile to be formed. For example, such a geotextile can form protection against water penetration for a building or a drain, such as the drain illustrated in FIG. 5. The coating can be achieved by projection or impregnation, or by crushing loosened soil.

FIG. 2 shows that, in a particular embodiment of the method that is the object of the present invention, during a step 205, plants are introduced as input, in the form of large-sized plants, typically stems measuring up to 2.5 m.

During a step 210, stem plants, in the form of large-sized plants, are partially reduced to form stem elements preferably more than twenty centimeters long and, even more preferably, more than fifty centimeters long.

During a step 220, the plants are crushed to form a mat of crushed plant stems more than five millimeters in diameter, plant stem fragments and raw plant fibers partially attached to said crushed stems.

During a step 225, the stems and/or the fibers are oriented so as to be oriented according to at least two different directions.

During a step 230, the thickness of the plant fiber mat is equalized.

During a step 235, ropes or cables are incorporated into the fibers, parallel to the greatest length of the fiber mat.

During a step 240, mechanical connections are created between the fibers of the mat, in the depth of the mat, by spraying water under pressure onto the plant fibers or, in a variant, with a multi-needle quilting machine (needlepunching).

As can be seen by reading the description above, thanks to the utilization of the present invention, a nonwoven geotextile is created with mechanical properties similar to, or even better than, those of known geotextiles, at lower cost.

During an optional step 245, this geotextile can be coated, in particular with soil, for example clay-based.

FIG. 3 shows, in a mat 125, crushed plant stems 305 more than five millimeters in diameter, small raw stems and stem fragments 310 (several centimeters to several tens of centimeters long, 0.1 to 1 centimeter in diameter) and plant fibers 315, interwoven. A portion of the plant fibers are attached to the crushed stems.

FIG. 4 shows, in a nonwoven geotextile 110, crushed plant stems 305 connected mechanically by stem fragments, plant fibers and fine matter binding, between them, the stems 305.

It is noted that utilizing entirely natural stems provides geotextiles with different Thicknesses—and therefore different grammages—than the nonwoven products known from the prior art. For example, the geotextile that is the object of the present invention has a weight of 200 to 5,000 g/m², and preferably between 400 and 1,000 g/m².

FIG. 5 shows a nonwoven geotextile 405 coated with clay 410 for forming a drain, here covered with stones 415. The geotextile 405 provides the structure and the clay 410 ensures the impermeability, partial or complete, of the drain thus formed. The stones 415 hold the geotextile in place and prevent the drain being quickly blocked by leaves, for example. The drained water therefore flows around stones over the clay layer 410 coating the geotextile 405.

In the embodiment illustrated in FIG. 4, a second layer of geotextile that is the object of the present invention 420 is positioned above the first, to hold the intermediate elements in place. In the case where there is no stone between the two layers of geotextile 405 and 420, the upper layer serves to hold the clay in place between the two layers. Preferably, in this case, the geotextile layer 420 is less coarse than the geotextile layer 405. 

1-16. (canceled)
 17. Nonwoven geotextile, that comprises: crushed plant stems more than five millimeters in diameter, plant stem fragments, and plant fibers partially attached to said crushed stems, wherein the plant stems and the plant stem fragments are interwoven by means of mechanical connections produced by spraying water.
 18. Geotextile according to claim 17, wherein said plants comprise hemp.
 19. Geotextile according to claim 18, wherein the stems, stem fragments and plant fibers are coated with soil.
 20. Geotextile according to claim 17, wherein the stems, stem fragments and plant fibers are coated with soil.
 21. Geotextile according to claim 20, wherein the soil comprises clay.
 22. Device for producing a nonwoven geotextile, that comprises: a means for arranging plants into a mat comprising crushed plant stems more than five millimeters in diameter, plant stem fragments, and plant fibers partially attached to said crushed stems; and a means for spraying water onto said mat so as to form mechanical connections between the crushed plant stems, the plant stem fragments and the plant fibers of said mat.
 23. Device according to claim 22, wherein said plants comprise hemp.
 24. Device according to claim 23, that comprises a means of coating the plant fiber mat with soil.
 25. Device according to claim 22, that comprises a means of coating the plant fiber mat with soil.
 26. Device according to claim 25, wherein the means of coating the plant fiber mat is designed to coat the plant fiber mat with soil comprising clay.
 27. Device according to claim 22, wherein the means for arranging plants into a mat of plant fibers comprises a means of crushing and/or carding plants.
 28. Device according to claim 22, wherein the means for arranging plants into a plant fiber mat comprises a means of orienting fibers according to at least two different orientations, through the vibrating action of a carrier.
 29. Device according to claim 22, wherein the means for arranging plants into a plant fiber mat comprises a means of orienting fibers according to at least two different orientations by intersecting supply paths.
 30. Device according to claim 22, wherein the means for arranging plants into a plant fiber mat comprises a device for incorporating ropes or cables, parallel to the greatest length of the mat, intended to serve as guides.
 31. Device according to claim 22, wherein the means for arranging plants into a plant fiber mat comprises a means of equalizing the thickness of the plant fiber mat.
 32. Method for producing a nonwoven geotextile, that comprises: a step of arranging plants into a mat comprising crushed plant stems more than five millimeters in diameter, plant stem fragments, and plant fibers partially attached to said crushed stems; and a step of spraying water onto said mat so as to form mechanical connections between the crushed plant stems, the plant stem fragments and the plant fibers of said mat.
 33. Method according to claim 32, wherein said plants comprise hemp.
 34. Method according to claim 33, that comprises a step of coating the plant fiber mat with soil.
 35. Method according to claim 32, that comprises a step of coating the plant fiber mat with soil.
 36. Method according to claim 35, wherein, during the plant fiber mat coating step, the plant fiber mat is coated with soil comprising clay. 